1. Field of the Invention
The present invention relates to a heat exhaust system, and more particularly to a self-stabilizing heat exhaust system.
2. Description of the Prior Art
As the electric device progresses in performance, a heat exhaust system becomes indispensable for dissipating the heat generated by the electric device. The heat generated by the electric device should be properly dissipated, otherwise the performance may be encumbered with the accumulated heat or the worst burns the electric devices. For example, a computer may be equipped with a heat exhaust system including several fans for dissipating the heat generated by a CPU or a power supply. The heat exhaust system is connected to the control port of the computer, and controlled by the control circuit built in the computer. Once some fan is failed, if the other normal fans in the system do not compensate the decreased heat exhaust ability as soon as possible, the result may be terrible.
A conventional heat exhaust system shown in FIG. 1 includes a heat-generating device 10, such as a computer, and several fans 30, such as a first fan 30a, a second fan 30b and a third fan 30c. Among these, the heat-generating device 10 further includes a control circuit 20, such as a logic control circuit. The control circuit 20 has a speed signal input terminal 21, a speed control terminal 22. The fan 30 has a power-input terminal 31, a grounded terminal 32, a signal-output terminal 33(O/P) and a signal-input terminal 35(I/P).
Still referring to FIG. 1, each signal-output terminal 33 of the fan 30 is electrically connected to the speed signal input terminal 21 of the control circuit 20. Therefore, the control circuit 20 can receive a speed signal representing that the rotation rate of the fan 30 is normal or abnormal. In general, if the rotation rate is normal, the speed signal is a high-level signal. On the contrary, if the rotation rate is abnormal, the speed signal is a low-level signal. However, the low-level signal may indicate that the rotation rate is normal, and the high-level signal may indicate that the rotation rate is abnormal. The signal-input terminal 35 of the fan 30 is electrically connected to the speed control terminal 22 of the control circuit 20. Therefore, the control circuit 20 can send a speed control signal to the fan 30a-c to control the speed of the fan.
Still referring to FIG. 1, when some fan, such as the first fan 30a, is failed, the control circuit 20 received an abnormal signal from the failed fan 30a. Then, the control circuit 20 sends a signal to the second fan 30b and the third fan 30c to increase the rotation rate of the fans 30b and 30c. In this manner, the decreased heat exhaust ability, caused by the failed first fan 30a, can be compensated by the higher rotation rate provided by the normal fans.
According to the above-mentioned conventional heat exhaust system, it is understood that the heat-generating device 10, such as the computer, detects which fan is failed and then the external control circuit activates the compensation. That is, the conventional heat exhaust system itself cannot detect and self-control whether the speed of the fan should be increased or not. The conventional heat exhaust system inherently includes several disadvantages as follows. First, the complexity of the heat-generating device is increased due to the addition of the heat exhaust system. An external control circuit, such as a logic control circuit, is required and thus built in the heat-generating device. As increase in the number of fans, the fan-out ability of the logic control circuit should be increased at the same time. As a result, the cost of the logic control circuit is increased.
Therefore, there is a need in the art for resolving the above disadvantages.
Therefore, the main object of the present invention is to provide a novel heat exhaust system can overcome the aforementioned problems. Besides, the above object of the present invention is achieved by a self-stabilizing heat exhaust system.
The present invention disclosed a self-stabilizing heat exhaust system including a plurality of devices for exhausting heat, such as fans. When all the fans are normal, each of the fans rotates at lower rotation rate. Once some fan fails, an adjacent fan will be switched to rotate at a higher rotation rate. For example, the value of the higher rotation rate may be two times of that of the lower rotation rate. Alternatively, the remaining fans start to rotate at the higher rotation rate so as to compensate the decreased exhaust ability. That is, the system of the present invention responds to the failed fan and then increases the exhaust ability of the normal fans. Thus, the inlet airflow and the outlet airflow can be kept steadily. Therefore, the heat-generating device, such as a computer, connected to the present system substantially does not experience problem in heat exhaust. Especially, the present invention does not need to co-operate with an external logic control circuit. That is, the present invention does not need to be connected to any logic control circuit built in the computer via a control port because the fan of the present system is able to detect the condition of each other and then vary the rotation rate by itself.
In sum, the present system is independent of the heat-generating device. There is free of any connection between the present system and the heat-generating device. Therefore, the complexity of the heat-generating device can be reduces significantly.